1. Field of the Invention
This invention relates to a useful intraocular irrigating solution. More particularly, this invention relates to a useful intraocular irrigating solution characterized by containing S-(.alpha.,.beta.-dicarboxyethyl)glutathione, which is a physiological substance, or an ester thereof, or a pharmacologically acceptable salt thereof.
2. Description of the Prior Art
With the recent progress and spread of cataract surgery and other ophthalmic surgery such as transplantation of the cornea, iris and vitreous body, there is a need for an intraocular irrigating solution effective enough to protect the intraocular tissues against damage during such operations. If the protection of intraocular tissues during operation is inadequate and the tissues sustain physiologic damage, the postoperative course will be unfavorable with an increased risk of complications such as corneal opacity, glaucoma and retinitis.
Any intraocular irrigating solution desirably approximates the human aqueous humor in composition but so far physiological saline, lactated Ringer's solution, BSS (balanced salt solution) PLUS (trade name), etc. have been chiefly utilized for intraocular irrigation and lavage.
However, these intraocular irrigating solutions are not sufficiently satisfactory for the protection of intraocular tissues and as far as BSS PLUS is concerned, it is not as stable as desired. Therefore, much research is underway for the development of a more stable, more tissue-protective intraocular irrigating solution.
Meanwhile, according to Kinseg et al., a desirable intraocular irrigating solution is composed of 8.33 mM glucose, 1.23 mM calcium, 1.22 mM magnesium and 25 mM sodium hydrogen carbonate and has a pH value of 7.4. However, this intraocular irrigating solution has the disadvantage that the calcium contained therein tends to precipitate with aging. As inhibitors of precipitation of calcium, several compounds can be contemplated but in order that such compounds may occur in amounts necessary to prevent precipitations as to inflict damages on the intraocular tissues. Thus, there is no agent as of today that is able to effectively prevent precipitation of calcium and yet keep the intraocular tissues intact and safe.
Under the circumstances the inventors of this invention, who had been studying the pharmacologic actions of S-(.alpha.,.beta.-dicarboxyethyl)glutathione, which is a physiological substance occurring comparatively abundantly in the crystalline lens, in particular, or an ester thereof, or a pharmacologically acceptable salt thereof, discovered that any of these compounds not only exerts an excellent protective action on the intraocular tissues but also is useful for the inhibition of precipitation of calcium. This discovery was followed by further intensive research, which has culminated in the development of this invention.